docs: def SA_partial_sphere(D, h):
      r'''Calculates surface area of a partial sphere according to [1]_.
      If h is half of D, the shape is half a sphere. No bottom is considered in
      this function. Valid inputs are positive values of D and h, with h always
      smaller or equal to D.
  
      .. math::
          a = \sqrt{h(2r - h)}
  
      .. math::
          A = \pi(a^2 + h^2)
  
      Parameters
      ----------
      D : float
          Diameter of the sphere, [m]
      h : float
          Height, as measured from the cap to where the sphere is cut off [m]
  
      Returns
      -------
      SA : float
          Surface area [m^2]
  
      Examples
      --------
      >>> SA_partial_sphere(1., 0.7)
      2.199114857512855
  
      References
      ----------
      .. [1] Weisstein, Eric W. "Spherical Cap." Text. Accessed December 22, 2015.
         http://mathworld.wolfram.com/SphericalCap.html.'''
      r = D*0.5
      a = (h*(2.*r - h))**0.5
      return pi*(a*a + h*h)